138 lines
2.5 KiB
Plaintext
138 lines
2.5 KiB
Plaintext
|
|
package DataStructures.Trees;
|
|
|
|
/*
|
|
* Avl is algo that balance itself while adding new alues to tree
|
|
* by rotating branches of binary tree and make itself Binary seaarch tree
|
|
* there are four cases which has to tackle
|
|
* rotating - left right ,left left,right right,right left
|
|
|
|
Test Case:
|
|
|
|
AVLTree tree=new AVLTree();
|
|
tree.insert(20);
|
|
tree.insert(25);
|
|
tree.insert(30);
|
|
tree.insert(10);
|
|
tree.insert(5);
|
|
tree.insert(15);
|
|
tree.insert(27);
|
|
tree.insert(19);
|
|
tree.insert(16);
|
|
|
|
tree.display();
|
|
|
|
|
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
public class AVLTree {
|
|
private class Node{
|
|
int data;
|
|
int height;
|
|
Node left;
|
|
Node right;
|
|
Node(int data){
|
|
this.data=data;
|
|
this.height=1;
|
|
}
|
|
|
|
}
|
|
private Node root;
|
|
public void insert(int data) {
|
|
this.root=insert(this.root,data);
|
|
}
|
|
private Node insert(Node node,int item) {
|
|
if(node==null) {
|
|
Node add=new Node(item);
|
|
return add;
|
|
}
|
|
if(node.data>item) {
|
|
node.left=insert(node.left,item);
|
|
}
|
|
if(node.data<item) {
|
|
node.right=insert(node.right,item);
|
|
}
|
|
node.height=Math.max(height(node.left),height(node.right))+1;
|
|
int bf=bf(node);
|
|
//LL case
|
|
if(bf>1&&item<node.left.data)
|
|
return rightRotate(node);
|
|
//RR case
|
|
if(bf<-1&&item>node.right.data)
|
|
return leftRotate(node);
|
|
//RL case
|
|
if(bf<-1&&item<node.right.data) {
|
|
node.right=rightRotate(node.right);
|
|
return leftRotate(node);
|
|
}
|
|
//LR case
|
|
if(bf>1&&item>node.left.data) {
|
|
node.left=leftRotate(node.left);
|
|
return rightRotate(node);
|
|
}
|
|
|
|
return node;
|
|
}
|
|
public void display() {
|
|
this.display(this.root);
|
|
System.out.println(this.root.height);
|
|
}
|
|
private void display (Node node) {
|
|
String str="";
|
|
if(node.left!=null)
|
|
str+=node.left.data+"=>";
|
|
else
|
|
str+="END=>";
|
|
str+=node.data+"";
|
|
if(node.right!=null)
|
|
str+="<="+node.right.data;
|
|
else
|
|
str+="<=END";
|
|
System.out.println(str);
|
|
if(node.left!=null)
|
|
display(node.left);
|
|
if(node.right!=null)
|
|
display(node.right);
|
|
}
|
|
private int height(Node node) {
|
|
if(node==null) {
|
|
return 0;
|
|
}
|
|
return node.height;
|
|
|
|
}
|
|
private int bf(Node node) {
|
|
if(node==null)
|
|
return 0;
|
|
return height(node.left)-height(node.right);
|
|
}
|
|
|
|
private Node rightRotate(Node c) {
|
|
Node b=c.left;
|
|
Node T3=b.right;
|
|
|
|
b.right=c;
|
|
c.left=T3;
|
|
c.height=Math.max(height(c.left),height(c.right))+1;
|
|
b.height=Math.max(height(b.left),height(b.right))+1;
|
|
return b;
|
|
|
|
}
|
|
private Node leftRotate(Node c) {
|
|
Node b=c.right;
|
|
Node T3=b.left;
|
|
|
|
b.left=c;
|
|
c.right=T3;
|
|
c.height=Math.max(height(c.left),height(c.right))+1;
|
|
b.height=Math.max(height(b.left),height(b.right))+1;
|
|
return b;
|
|
|
|
}
|
|
|
|
}
|